Logic considered fun

This report describes the development and use of an online teaching tool giving students exercises in logical modelling, or \emph{formalisation} as it is called in the older literature. The original version of the site, `Logic for Fun', dates from 2001, though it was little used except by small groups of students at the Australian National University. It is currently in the process of being replaced by a new version, free to all Internet users, intended to be promoted widely as a useful addition to both online and traditional logic courses.